Don't sculpt muscles in Maya, it will be such a big headache. Just work on getting the correct proportions and shapes first. The sculpt tool is mostly just for pulling/pushing a lot of verts. I've never actually seen someone sculpt with it.
ah yes, much easier to see whats going on there now... well the references don't have much detail, but the overall proportions are spot on, which is what you need... looking at the side view you can probably tell pretty easily that you need to work on that view the most... its almost right in the front view, but quite off…
it seems that you have gotten the overall proportions right. the head is still way too blocky, it needs some additional horizontal edgeloops. not much 2-3 should suffice. this is just so you can smooth it out to get a rounder shape for the head. from here you could try to subdivide the mesh and start blocking out muscle…